JP3532741B2 - Heavy metal recovery method in fly ash - Google Patents
Heavy metal recovery method in fly ashInfo
- Publication number
- JP3532741B2 JP3532741B2 JP23203297A JP23203297A JP3532741B2 JP 3532741 B2 JP3532741 B2 JP 3532741B2 JP 23203297 A JP23203297 A JP 23203297A JP 23203297 A JP23203297 A JP 23203297A JP 3532741 B2 JP3532741 B2 JP 3532741B2
- Authority
- JP
- Japan
- Prior art keywords
- lead
- zinc
- solid
- fly ash
- liquid separation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000010881 fly ash Substances 0.000 title claims description 27
- 238000000034 method Methods 0.000 title claims description 16
- 229910001385 heavy metal Inorganic materials 0.000 title claims description 10
- 238000011084 recovery Methods 0.000 title description 8
- 229910052725 zinc Inorganic materials 0.000 claims description 40
- 239000011701 zinc Substances 0.000 claims description 40
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 39
- 239000007788 liquid Substances 0.000 claims description 33
- 238000000926 separation method Methods 0.000 claims description 24
- 239000003795 chemical substances by application Substances 0.000 claims description 23
- 239000000706 filtrate Substances 0.000 claims description 23
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Natural products CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 19
- 239000000126 substance Substances 0.000 claims description 10
- -1 acetic acid compound Chemical class 0.000 claims description 9
- 230000002378 acidificating effect Effects 0.000 claims description 8
- 239000003002 pH adjusting agent Substances 0.000 claims description 7
- 230000008018 melting Effects 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 description 22
- 238000003756 stirring Methods 0.000 description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 238000001556 precipitation Methods 0.000 description 9
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000004568 cement Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical group [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 3
- DPLVEEXVKBWGHE-UHFFFAOYSA-N potassium sulfide Chemical compound [S-2].[K+].[K+] DPLVEEXVKBWGHE-UHFFFAOYSA-N 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- HYHCSLBZRBJJCH-UHFFFAOYSA-M sodium hydrosulfide Chemical compound [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 description 3
- 235000011121 sodium hydroxide Nutrition 0.000 description 3
- 238000004065 wastewater treatment Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 2
- 239000005083 Zinc sulfide Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000001632 sodium acetate Substances 0.000 description 2
- 235000017281 sodium acetate Nutrition 0.000 description 2
- 229910052979 sodium sulfide Inorganic materials 0.000 description 2
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 150000004763 sulfides Chemical class 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052984 zinc sulfide Inorganic materials 0.000 description 2
- DRDVZXDWVBGGMH-UHFFFAOYSA-N zinc;sulfide Chemical compound [S-2].[Zn+2] DRDVZXDWVBGGMH-UHFFFAOYSA-N 0.000 description 2
- GHYOCDFICYLMRF-UTIIJYGPSA-N (2S,3R)-N-[(2S)-3-(cyclopenten-1-yl)-1-[(2R)-2-methyloxiran-2-yl]-1-oxopropan-2-yl]-3-hydroxy-3-(4-methoxyphenyl)-2-[[(2S)-2-[(2-morpholin-4-ylacetyl)amino]propanoyl]amino]propanamide Chemical compound C1(=CCCC1)C[C@@H](C(=O)[C@@]1(OC1)C)NC([C@H]([C@@H](C1=CC=C(C=C1)OC)O)NC([C@H](C)NC(CN1CCOCC1)=O)=O)=O GHYOCDFICYLMRF-UTIIJYGPSA-N 0.000 description 1
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 1
- 239000005695 Ammonium acetate Substances 0.000 description 1
- 101100002917 Caenorhabditis elegans ash-2 gene Proteins 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical class S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001339 alkali metal compounds Chemical class 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 229910052977 alkali metal sulfide Inorganic materials 0.000 description 1
- 150000001341 alkaline earth metal compounds Chemical class 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 235000019257 ammonium acetate Nutrition 0.000 description 1
- 229940043376 ammonium acetate Drugs 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 229940125797 compound 12 Drugs 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-M hydrosulfide Chemical compound [SH-] RWSOTUBLDIXVET-UHFFFAOYSA-M 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052981 lead sulfide Inorganic materials 0.000 description 1
- 229940056932 lead sulfide Drugs 0.000 description 1
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 description 1
- GLNWILHOFOBOFD-UHFFFAOYSA-N lithium sulfide Chemical compound [Li+].[Li+].[S-2] GLNWILHOFOBOFD-UHFFFAOYSA-N 0.000 description 1
- HXQGSILMFTUKHI-UHFFFAOYSA-M lithium;sulfanide Chemical compound S[Li] HXQGSILMFTUKHI-UHFFFAOYSA-M 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000010813 municipal solid waste Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 235000011056 potassium acetate Nutrition 0.000 description 1
- ZOCLAPYLSUCOGI-UHFFFAOYSA-M potassium hydrosulfide Chemical compound [SH-].[K+] ZOCLAPYLSUCOGI-UHFFFAOYSA-M 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 125000000101 thioether group Chemical group 0.000 description 1
- 239000000052 vinegar Substances 0.000 description 1
- 235000021419 vinegar Nutrition 0.000 description 1
- UGZADUVQMDAIAO-UHFFFAOYSA-L zinc hydroxide Chemical compound [OH-].[OH-].[Zn+2] UGZADUVQMDAIAO-UHFFFAOYSA-L 0.000 description 1
- 229910021511 zinc hydroxide Inorganic materials 0.000 description 1
- 229940007718 zinc hydroxide Drugs 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Processing Of Solid Wastes (AREA)
- Manufacture And Refinement Of Metals (AREA)
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、都市ごみなどの廃
棄物を焼却または溶融することによって排ガスとともに
排出される飛灰中の亜鉛および鉛の回収方法に関するも
のである。
【０００２】
【従来の技術】従来、都市ごみなどの廃棄物を焼却また
は溶融した際に排ガスとともに排出される亜鉛、鉛など
の重金属類を含む飛灰は、セメント固化法、薬剤処理法
等により安定化処理されたのちに埋立処分されている。
セメント固化法は、飛灰を十分な量のセメントと均質に
混練し造粒または形成したものを十分に養生して固化す
る方法である。また、薬剤処理法は、飛灰を十分な量の
薬剤と均質に混練し、重金属が溶出しないように化学的
に安定化する方法である。
【０００３】
【発明が解決しようとする課題】しかしながら、長期的
に見た場合、これらの方法では、亜鉛、鉛などの重金属
の溶出防止はまだ十分であるとは言えず、また、埋立地
の確保が困難であることなどから、飛灰の減容化、再資
源化が望まれている。本発明は、飛灰中に含まれる亜
鉛、鉛を除去することにより飛灰を安定化するととも
に、除去した亜鉛、鉛を効率的に回収する飛灰中の重金
属回収方法を提供することを目的とするものである。
【０００４】
【課題を解決するための手段】本発明は、このような課
題を解決するものであって、本発明の要旨は、焼却炉ま
たは溶融炉から排出される亜鉛および鉛を含有する飛灰
に、酸性薬剤を添加して亜鉛を抽出した後、固液分離
し、次いで以下の（ａ）工程および（ｂ）工程を行うこ
とを特徴とする飛灰中の重金属回収方法である。
（ａ）工程：前記固液分離して得られた亜鉛を含む濾液
に、ｐＨ調整剤および不溶化剤を添加して亜鉛を不溶化
物として回収する工程。
（ｂ）工程：前記固液分離して得られた鉛を含む残渣
に、酢酸化合物を添加して鉛を抽出した後、固液分離
し、次いで、固液分離して得られた鉛を含む濾液に、不
溶化剤を添加して鉛を不溶化物として回収する工程。
【０００５】以下、本発明を詳細に説明する。本発明に
おいては、まず、重金属類を含有する飛灰に、酸性薬剤
を添加して亜鉛を抽出することが必要である。本発明に
用いられる酸性薬剤としては、塩酸、硫酸、硝酸、燐酸
などの鉱酸などが挙げられる。酸性薬剤の添加量として
は、飛灰に酸性薬剤を添加して攪拌した後のｐＨが１以
下となるように添加するのが好ましい。ｐＨが１を超え
る場合には、飛灰からの亜鉛の抽出が不十分となる傾向
があり好ましくない。
【０００６】このとき、酸性薬剤を加えて充分に攪拌す
ることが好ましく、その攪拌時間としては３０分〜６時
間が好ましい。攪拌時間が３０分未満である場合には、
亜鉛の抽出が不十分になりやすく、攪拌時間が６時間を
超える場合には、処理時間が長くなることで処理能力が
低下しやすくなるため、好ましくない。攪拌後、固液分
離することにより、亜鉛を含む濾液と鉛を含む残渣とに
分離される。
【０００７】次に、本発明においては、以下に説明する
（ａ）工程および（ｂ）工程を行う。本発明における
（ａ）工程では、固液分離して得られた亜鉛を含む濾液
に、ｐＨ調整剤および不溶化剤を添加して亜鉛を不溶化
物として回収する。
【０００８】本発明に用いられるｐＨ調整剤としては、
水酸化ナトリウム、水酸化カリウムなどのアルカリ金属
の水酸化物や、硫化ナトリウム、硫化カリウムなどのア
ルカリ金属の硫化物や、水硫化ナトリウム、水硫化カリ
ウムなどのアルカリ金属の水硫化物が挙げられる。ｐＨ
調整剤の添加量としては、亜鉛を含む濾液のｐＨが２〜
４となるように添加するのが好ましい。ｐＨが２以下の
場合には、不溶化剤を添加したときの亜鉛の不溶化が不
十分になりやすく、一方ｐＨが４を超える場合には、ラ
ンニングコストが高くなり好ましくない。
【０００９】本発明に用いられる不溶化剤としては、水
酸化ナトリウム、水酸化カリウム、水酸化リチウムなど
の水酸化物や、硫化ナトリウム、硫化カリウム、硫化リ
チウムなどの硫化物や、水硫化ナトリウム、水硫化カリ
ウム、水硫化リチウムなどの水硫化物が挙げられる。不
溶化剤の添加量としては、不溶化剤が水酸化物である場
合には、亜鉛を含む濾液のｐＨが７以上となるように添
加するのが好ましい。ｐＨが７未満の場合には、不溶化
物である水酸化亜鉛の生成が不十分となりやすく、亜鉛
の回収量が低下するので好ましくない。また、不溶化剤
が硫化物あるいは水硫化物である場合には、可溶化剤に
より抽出された濾液中の鉛１当量に対して、硫黄（Ｓ）
として０．５〜１０当量となるように添加するのが好ま
しい。不溶化剤の添加量が０．５当量未満である場合に
は、硫化亜鉛の生成が不十分となりやすく、亜鉛の回収
量が低下するので好ましくない。また、不溶化剤の添加
量が１０当量を超える場合には、ランニングコストが高
くなり好ましくない。このようにして不溶化剤により不
溶化したのち、固液分離することにより、飛灰中の亜鉛
を水酸化物または硫化物として回収することができる。
【００１０】一方、本発明における（ｂ）工程では、固
液分離して得られた鉛を含む残渣に、酢酸化合物を添加
して鉛を抽出した後、固液分離し、次いで、固液分離し
て得られた鉛を含む濾液に、不溶化剤を添加して鉛を不
溶化物として回収する。
【００１１】本発明に用いられる酢酸化合物としては、
酢酸アンモニウム、酢酸ナトリウム、酢酸カリウム、酢
酸リチウムなどが挙げられる。酢酸化合物の添加量とし
ては、飛灰中の重金属含有量およびアルカリ金属化合物
やアルカリ土類金属化合物の含有量などによっても異な
るが、通常、飛灰１ｋｇに対して、純分換算で０．０１
〜２０ｋｇが好ましく、１〜１０ｋｇがより好ましい。
また、その時の酢酸化合物の添加形態は水溶液として用
い、この濃度としては、０．１〜１０ｍｏｌ／リット
ル、特に２〜５ｍｏｌ／リットルが好ましく、この液量
としては、５００〜２０００ミリリットル、特に１００
０〜１５００ミリリットルが好ましい。酢酸化合物の添
加量が純分換算で０．０１ｋｇ未満の場合、また濃度が
０．１ｍｏｌ／リットル未満の場合、あるいは液量が５
００ミリリットル未満である場合には、残渣からの鉛の
抽出が不十分となる傾向があり好ましくない。また、酢
酸化合物の添加量が純分換算で２０ｋｇを超える場合、
また濃度が１０ｍｏｌ／リットルを超える場合、あるい
は液量が２０００ミリリットルを超える場合には、ラン
ニングコストが高くなるので、好ましくない。このと
き、酢酸化合物を加えて攪拌することが好ましく、その
攪拌時間としては３０分〜６時間が好ましく、攪拌後、
固液分離することにより、残渣と抽出された鉛を含む濾
液とに分離される。
【００１２】本発明における（ｂ）工程では、次いで、
抽出された鉛を含む濾液に不溶化剤を添加して鉛を不溶
化物とすることが必要である。ここで用いられる不溶化
剤としては、上記した（ａ）工程で用いられる不溶化剤
が同様に用いられる。不溶化剤により不溶化したのち、
固液分離することにより、飛灰中の鉛を水酸化物または
硫化物として回収することができる。
【００１３】本発明における固液分離方法としては、通
常、沈殿により固液分離を行うが、この方法に限定され
るものではなく、この他に、脱水や濾過による方法など
が挙げられる。
【００１４】次に、本発明を行うのに好適な装置の概略
図を図１に示す。図１において、飛灰１は、第一反応槽
２に送られる。第一反応槽２では、飛灰１と酸性薬剤３
とが攪拌混合される。次に第一反応槽２で攪拌混合され
たスラリーを第一沈殿槽４に送って固液分離し、亜鉛を
含む濾液は第二反応槽５に送られ、（ａ）工程に移され
る一方、鉛を含む残渣は第三反応槽１１に送られ、
（ｂ）工程に移される。第二反応槽５では、第一沈殿槽
４より送られた濾液にｐＨ調整剤６を添加してｐＨ調整
したのち不溶化剤７を添加して攪拌する。次に第二反応
槽５より第二沈殿槽８へ送液して固液分離し、沈殿物は
亜鉛回収物９となり、濾液は排水処理設備１０へ送られ
る。
【００１５】また、第三反応槽１１に送られた残渣に、
酢酸化合物１２が添加され攪拌混合される。次に第三沈
殿槽１３に送って固液分離し、濾液を第四反応槽１４に
送る。第四反応槽１４では、第三沈殿槽１３より送られ
てきた濾液に不溶化剤７を添加して攪拌する。次に、第
四反応槽１４より第四沈殿槽１５へ送液して固液分離
し、沈殿物は鉛回収物１６となり、濾液は廃水処理設備
１０へ送られる。
【００１６】
【実施例】以下、実施例により本発明を具体的に説明す
る。
実施例１
焼却炉より排出されたＰｂを０．９４重量％（以下、％
は重量％を示す。）、Ｚｎを３．５６％、Ｃｕを１．１
７％、Ｎａを１３．９％、Ｃａを０．５３％含む焼却飛
灰５ｋｇを第一反応槽２に送り、ｐＨが０．５となるよ
うに硫酸５０リットルを添加して１時間攪拌した後、ス
ラリーを第一沈殿槽４に送って固液分離し、亜鉛を含む
濾液を第二反応槽５に送るとともに、鉛を含む残渣を第
三反応槽１１に送った。第二反応槽５にｐＨ調整剤とし
て純分換算１．４ｋｇ、濃度２２％、液量６リットルの
苛性ソーダを添加してｐＨ２．５とし、さらに不溶化剤
として純分換算０．１５ｋｇ、濃度２４％、液量０．５
リットルの水硫化ソーダを添加して亜鉛を硫化物とした
後、第二沈殿槽８へ送液して沈殿・濾過することにより
亜鉛の硫化物（亜鉛回収物９）と濾液とに固液分離し
た。また、鉛を含む残渣が送られた第三反応槽１１に、
可溶化剤として純分換算１ｋｇ、濃度２８％、液量３リ
ットルの酢酸ソーダを加えて１時間攪拌した後、スラリ
ーを第三沈殿槽１３に送って固液分離し、濾液を第四反
応槽１４に送った。第四反応槽１４に不溶化剤として純
分換算０．０１ｋｇ、濃度２４％、液量０．０４リット
ルＬの水硫化ナトリウムを添加して鉛を硫化物とした
後、第四沈殿槽１５へ送液して沈殿・濾過することによ
り鉛の硫化物（鉛回収物１６）と濾液とに固液分離し
た。上記のようにして得られた亜鉛および鉛の硫化物を
水により洗浄した。
【００１７】このようにして得られた亜鉛および鉛回収
物の組成分析結果ならびに亜鉛および鉛の回収率も表１
に示す。
【００１８】
【表１】
【００１９】この結果より、得られた亜鉛回収物中の亜
鉛含有濃度は、５９．９％であり、亜鉛回収率は、９
０．６％であった。また、得られた鉛回収物中の鉛含有
濃度は、５４．３％であり、鉛回収率は、８９．５％で
あった。このように焼却飛灰中に含有されていた亜鉛お
よび鉛は高効率で回収物中に分離、回収されており、回
収物は山元還元（廃棄物である飛灰から回収した鉛など
の金属類を、精錬原料として精錬会社に引き取ってもら
う）により再資源化することができるものであった。
【００２０】
【発明の効果】本発明によれば、飛灰中の亜鉛、鉛を回
収して山元還元することによって、有価物の再資源化お
よび環境保全の立場から好ましく、さらに埋立処分量の
減少による埋立処分地の延命化に寄与できる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering zinc and lead in fly ash discharged together with exhaust gas by incinerating or melting waste such as municipal waste. Things. 2. Description of the Related Art Conventionally, fly ash containing heavy metals such as zinc and lead discharged together with exhaust gas when incinerating or melting waste such as municipal solid waste is produced by a cement solidification method, a chemical treatment method or the like. It has been landfilled after being stabilized.
The cement solidification method is a method in which fly ash is uniformly kneaded with a sufficient amount of cement, granulated or formed, and fully cured and solidified. The chemical treatment method is a method in which fly ash is homogeneously kneaded with a sufficient amount of a chemical and chemically stabilized so that heavy metals do not elute. [0003] However, in the long term, it cannot be said that these methods are still sufficient to prevent the elution of heavy metals such as zinc and lead, and that landfills have not been reclaimed. Since it is difficult to secure it, it is desired to reduce the volume of fly ash and recycle it. An object of the present invention is to provide a method for recovering heavy metals in fly ash, which stabilizes the fly ash by removing zinc and lead contained in the fly ash and efficiently recovers the removed zinc and lead. It is assumed that. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the gist of the present invention is to provide a fly containing zinc and lead discharged from an incinerator or a melting furnace. A method for recovering heavy metals in fly ash, comprising adding an acidic agent to ash to extract zinc, performing solid-liquid separation, and then performing the following steps (a) and (b). Step (a): a step of adding a pH adjuster and an insolubilizing agent to the filtrate containing zinc obtained by the solid-liquid separation to recover zinc as an insolubilized substance. Step (b): the lead-containing residue obtained by the solid-liquid separation is added with an acetic acid compound to extract the lead, then subjected to solid-liquid separation, and then contains the lead obtained by solid-liquid separation. A step of adding an insolubilizing agent to the filtrate to recover lead as an insolubilized substance. Hereinafter, the present invention will be described in detail. In the present invention, it is necessary to first extract zinc by adding an acidic agent to fly ash containing heavy metals. Examples of the acidic drug used in the present invention include mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. It is preferable to add the acidic agent so that the pH after adding the acidic agent to the fly ash and stirring is 1 or less. If the pH exceeds 1, extraction of zinc from fly ash tends to be insufficient, which is not preferable. [0006] At this time, it is preferable to add an acidic agent and sufficiently stir the mixture, and the stirring time is preferably 30 minutes to 6 hours. If the stirring time is less than 30 minutes,
If the extraction of zinc is likely to be insufficient and the stirring time exceeds 6 hours, the processing time is prolonged and the processing capacity is likely to decrease, which is not preferable. After the stirring, the mixture is separated into a filtrate containing zinc and a residue containing lead by solid-liquid separation. Next, in the present invention, the steps (a) and (b) described below are performed. In the step (a) of the present invention, a pH adjuster and an insolubilizing agent are added to a zinc-containing filtrate obtained by solid-liquid separation to recover zinc as an insolubilized product. The pH adjuster used in the present invention includes:
Examples include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal sulfides such as sodium sulfide and potassium sulfide, and alkali metal hydrosulfides such as sodium and potassium hydrosulfide. pH
As the addition amount of the regulator, the pH of the filtrate containing zinc is 2 to 2.
It is preferable to add so as to be 4. When the pH is 2 or less, insolubilization of zinc when an insolubilizing agent is added tends to be insufficient. On the other hand, when the pH exceeds 4, the running cost increases, which is not preferable. The insolubilizing agent used in the present invention includes hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, sulfides such as sodium sulfide, potassium sulfide and lithium sulfide, sodium hydrosulfide and water. Hydrosulfides such as potassium sulfide and lithium hydrosulfide are exemplified. When the insolubilizing agent is a hydroxide, it is preferable to add the insolubilizing agent so that the pH of the filtrate containing zinc becomes 7 or more. When the pH is less than 7, the formation of zinc hydroxide, which is an insolubilized substance, tends to be insufficient, and the amount of recovered zinc is undesirably reduced. When the insolubilizing agent is a sulfide or a hydrosulfide, sulfur (S) is added to one equivalent of lead in the filtrate extracted by the solubilizing agent.
Is preferably added so as to be 0.5 to 10 equivalents. If the amount of the insolubilizing agent is less than 0.5 equivalent, the formation of zinc sulfide tends to be insufficient, and the amount of recovered zinc decreases, which is not preferable. On the other hand, if the amount of the insolubilizer exceeds 10 equivalents, the running cost is undesirably high. After being insolubilized by the insolubilizing agent in this way, by performing solid-liquid separation, zinc in fly ash can be recovered as hydroxide or sulfide. On the other hand, in the step (b) of the present invention, an acetic acid compound is added to a lead-containing residue obtained by solid-liquid separation to extract lead, followed by solid-liquid separation, and then solid-liquid separation. An insolubilizing agent is added to the lead-containing filtrate thus obtained, and the lead is recovered as an insolubilized substance. The acetic acid compound used in the present invention includes:
Examples thereof include ammonium acetate, sodium acetate, potassium acetate, and lithium acetate . The amount of the acetic acid compound to be added varies depending on the heavy metal content in the fly ash, the content of the alkali metal compound and the alkaline earth metal compound, and is usually 0.01 to 1 kg of the fly ash in terms of pure content.
-20 kg is preferable, and 1-10 kg is more preferable.
At this time, the acetic acid compound is added in the form of an aqueous solution, and the concentration is preferably 0.1 to 10 mol / L, particularly preferably 2 to 5 mol / L, and the liquid volume is 500 to 2,000 mL, particularly 100
0-1500 ml is preferred. When the added amount of the acetic acid compound is less than 0.01 kg in terms of pure content, when the concentration is less than 0.1 mol / liter, or when the liquid amount is 5
If the amount is less than 00 ml, extraction of lead from the residue tends to be insufficient, which is not preferable. Also, vinegar
If the amount of the acid compound exceeds 20 kg in terms of pure content,
On the other hand, when the concentration exceeds 10 mol / liter or when the amount of the liquid exceeds 2000 ml, the running cost increases, which is not preferable. At this time, it is preferable to add the acetic acid compound and stir, and the stirring time is preferably 30 minutes to 6 hours.
The solid-liquid separation separates the residue into a filtrate containing extracted lead. In the step (b) of the present invention,
It is necessary to add an insolubilizing agent to the filtrate containing the extracted lead to make the lead insoluble. As the insolubilizer used here, the insolubilizer used in the above-mentioned step (a) is similarly used. After being insolubilized by the insolubilizer,
By performing solid-liquid separation, lead in fly ash can be recovered as hydroxide or sulfide. [0013] The solid-liquid separation method in the present invention is usually carried out by solid-liquid separation by precipitation. However, the present invention is not limited to this method, and other methods include dehydration and filtration. Next, FIG. 1 shows a schematic view of an apparatus suitable for carrying out the present invention. In FIG. 1, fly ash 1 is sent to a first reaction tank 2. In the first reaction tank 2, fly ash 1 and acid chemical 3
Are mixed with stirring. Next, the slurry agitated and mixed in the first reaction tank 2 is sent to the first precipitation tank 4 for solid-liquid separation, and the filtrate containing zinc is sent to the second reaction tank 5 and transferred to the step (a). The residue containing lead is sent to the third reaction tank 11,
It moves to (b) process. In the second reaction tank 5, a pH adjuster 6 is added to the filtrate sent from the first precipitation tank 4 to adjust the pH, and then an insolubilizing agent 7 is added and stirred. Next, the solution is sent from the second reaction tank 5 to the second precipitation tank 8 to be separated into a solid and a liquid. The precipitate becomes a recovered zinc 9 and the filtrate is sent to a wastewater treatment facility 10. The residue sent to the third reaction tank 11 includes:
Acetic acid compound 12 is added and mixed with stirring. Next, the filtrate is sent to the third precipitation tank 13 for solid-liquid separation, and the filtrate is sent to the fourth reaction tank 14. In the fourth reaction tank 14, the insolubilizing agent 7 is added to the filtrate sent from the third precipitation tank 13 and stirred. Next, the solution is sent from the fourth reaction tank 14 to the fourth precipitation tank 15 to be separated into solid and liquid. The precipitate becomes a lead recovery product 16, and the filtrate is sent to the wastewater treatment equipment 10. The present invention will be described below in detail with reference to examples. Example 1 Pb discharged from an incinerator was 0.94% by weight (hereinafter,%
Indicates% by weight. ), 3.56% Zn and 1.1% Cu
5 kg of incinerated fly ash containing 7%, 13.9% of Na and 0.53% of Ca was sent to the first reaction tank 2, and 50 liters of sulfuric acid was added so that the pH became 0.5, followed by stirring for 1 hour. Thereafter, the slurry was sent to the first settling tank 4 for solid-liquid separation, the filtrate containing zinc was sent to the second reaction tank 5, and the residue containing lead was sent to the third reaction tank 11. To the second reaction tank 5 was added 1.4 kg of pure content as a pH adjuster, a concentration of 22%, and a 6 liter solution of caustic soda to a pH of 2.5. Further, 0.15 kg of pure content as an insolubilizer and a concentration of 24% were added. , Liquid volume 0.5
After adding 1 liter of sodium hydrosulfide to convert zinc into sulfide, the solution is sent to the second precipitation tank 8, and precipitated and filtered to separate solid and liquid into zinc sulfide (zinc recovered product 9) and filtrate. did. In addition, the third reaction tank 11 to which the residue containing lead was sent,
After adding 1 kg of pure content as a solubilizing agent, sodium acetate having a concentration of 28% and a liquid volume of 3 liters, and stirring for 1 hour, the slurry is sent to the third sedimentation tank 13 for solid-liquid separation, and the filtrate is subjected to the fourth reaction tank. Sent to 14. After adding 0.01 kg of pure content as a solubilizer to the fourth reaction tank 14 at a concentration of 24% and a solution volume of 0.04 liter of sodium hydrosulfide to convert lead into sulfide, the mixture is sent to the fourth precipitation tank 15. The solution was precipitated and filtered to separate solid and liquid into lead sulfide (lead recovery product 16) and filtrate. The sulfides of zinc and lead obtained as described above were washed with water. The results of the composition analysis of the recovered zinc and lead and the recovery of zinc and lead are shown in Table 1.
Shown in [Table 1] From the results, the zinc content in the obtained zinc recovery was 59.9%, and the zinc recovery was 99.9%.
0.6%. The lead content of the obtained lead was 54.3%, and the lead recovery was 89.5%. As described above, zinc and lead contained in incinerated fly ash are separated and recovered with high efficiency in the recovered material, and the recovered material is reduced by yamamoto (metals such as lead recovered from fly ash as waste). Is collected by a smelting company as a smelting raw material). According to the present invention, by recovering zinc and lead in fly ash and reducing them at the hill, it is preferable from the standpoint of recycling valuable resources and protecting the environment. This can contribute to extending the life of landfill sites due to the decrease.
【図面の簡単な説明】
【図１】本発明の飛灰中の重金属回収方法に好適に用い
られる装置の一例を示す概略フロー図である。
【符号の説明】
１ 飛灰
２ 第一反応槽
３ 酸性薬剤
４ 第一沈殿槽
５ 第二反応槽
６ ｐＨ調整剤
７ 不溶化剤
８ 第二沈殿槽
９ 亜鉛回収物
１０ 排水処理設備
１１ 第三反応槽
１２ 可溶化剤
１３ 第三沈殿槽
１４ 第四反応槽
１５ 第四沈殿槽
１６ 鉛回収物
１７ 残渣BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic flow chart showing an example of an apparatus suitably used for the method for recovering heavy metals in fly ash according to the present invention. [Description of Signs] 1 Fly ash 2 First reaction tank 3 Acidic agent 4 First settling tank 5 Second reaction tank 6 pH adjuster 7 Insolubilizer 8 Second settling tank 9 Zinc collection 10 Wastewater treatment equipment 11 Third reaction Tank 12 Solubilizer 13 Third settling tank 14 Fourth reaction tank 15 Fourth settling tank 16 Lead recovery 17 Residue
フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ Ｃ２２Ｂ 19/00 Ｃ２２Ｂ 13/04 19/30 19/22 (58)調査した分野(Int.Cl.7，ＤＢ名) C22B 1/00 - 61/00 B09B 3/00 Continuation of the front page (51) Int.Cl. 7 identification code FI C22B 19/00 C22B 13/04 19/30 19/22 (58) Investigated field (Int.Cl. 7 , DB name) C22B 1/00- 61/00 B09B 3/00
Claims (1)
および鉛を含有する飛灰に、酸性薬剤を添加して亜鉛を
抽出した後、固液分離し、次いで以下の（ａ）工程およ
び（ｂ）工程を行うことを特徴とする飛灰中の重金属回
収方法。 （ａ）工程：前記固液分離して得られた亜鉛を含む濾液
に、ｐＨ調整剤および不溶化剤を添加して亜鉛を不溶化
物として回収する工程。 （ｂ）工程：前記固液分離して得られた鉛を含む残渣
に、酢酸化合物を添加して鉛を抽出した後、固液分離
し、次いで、固液分離して得られた鉛を含む濾液に、不
溶化剤を添加して鉛を不溶化物として回収する工程。(57) [Claims] [Claim 1] Zinc discharged from an incinerator or melting furnace
And fly ash containing lead, after extracting the zinc with the addition of acidic agent, solid-liquid separation, and then the following step (a) and (b) heavy metals in fly ash, characterized in that a step Collection method. Step (a): a step of adding a pH adjuster and an insolubilizing agent to the filtrate containing zinc obtained by the solid-liquid separation to recover zinc as an insolubilized substance. Step (b): The lead-containing residue obtained by the solid-liquid separation is added with an acetic acid compound to extract lead, then subjected to solid-liquid separation, and then contains the lead obtained by solid-liquid separation. A step of adding an insolubilizing agent to the filtrate to recover lead as an insolubilized substance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23203297A JP3532741B2 (en) | 1997-08-28 | 1997-08-28 | Heavy metal recovery method in fly ash |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23203297A JP3532741B2 (en) | 1997-08-28 | 1997-08-28 | Heavy metal recovery method in fly ash |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1161286A JPH1161286A (en) | 1999-03-05 |
| JP3532741B2 true JP3532741B2 (en) | 2004-05-31 |
Family
ID=16932910
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23203297A Expired - Lifetime JP3532741B2 (en) | 1997-08-28 | 1997-08-28 | Heavy metal recovery method in fly ash |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3532741B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3619069B2 (en) * | 1999-08-09 | 2005-02-09 | ユニチカ株式会社 | Fly ash recycling process |
| JP2001049360A (en) * | 1999-08-12 | 2001-02-20 | Unitika Ltd | Process for recovering lead in fly ash |
-
1997
- 1997-08-28 JP JP23203297A patent/JP3532741B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH1161286A (en) | 1999-03-05 |
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